PROJECT SUMMARY This new T32 application represents a one-of-kind interdisciplinary training program at the intersection of implementation science and mental health at the University of Pennsylvania (Penn). Penn offers a unique environment in which to train early-stage investigators, given its longstanding commitment to postdoctoral training. Over the past three decades, faculty in Penn's Center for Mental Health Policy and Services Research (CMHPSR) have collaborated closely with community agencies, including Philadelphia's Departments of Health and Behavioral Health, the School District of Philadelphia, the criminal justice system, and Federally Qualified Health Centers. Through these partnerships, we will create unique opportunities to embed postdoctoral trainees in the settings in which they hope to conduct implementation research. Penn has emerged as a leader in implementation science, with numerous resources including a working group with seed money for pilot projects and a graduate-level course. The proposed training program includes six experienced investigators from Penn in the School of Medicine and three community partners as part of the core executive committee. Additional mentors are available from other schools at Penn including the Wharton School of Business to encourage interdisciplinary inquiry and cutting-edge knowledge; as well as investigators from other local institutions (Drexel, Temple). Further, a group of national leaders in implementation science (senior scholars) also will interact with trainees every other month. We propose the following aims for our T32: (1) expose postdoctoral fellows to foundational and cutting edge didactic training in implementation science and other related disciplines through one core course (Implementation Science in Health and Healthcare), a monthly seminar (Seminar on Implementation Science), and electives as needed; (2) provide a mentorship team that includes depth and breadth, always including a core member of the executive committee, a leader at a community agency, and an additional content mentor if needed; and (3) embed trainees at a community site to develop and conduct a small implementation project in partnership with stakeholders; this small project will lead to external funding appropriate for early-stage investigators (F32, K, R03, R21, or equivalent). The proposed T32 will bring together trainees and mentors from multiple disciplines, which will create a fertile environment in which to train the next generation of implementation scientists. Our long-standing collaborations with community partners are harnessed to increase the ecological validity of research questions and results. Successful trainees will be future leaders in reducing the research-to-practice gap and scaling up the use of evidence-based practices in community settings.